1. Field of the Invention
The present invention relates to a storage container for storing light-sensitive storage radiation screens.
2. Description of Related Art
A variety of storage layer radiation screens have been developed for recording radiation images created by exposing the screen to a radiation source, such as x-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays and ultraviolet rays. When radiation is passed through an object onto the screen, the radiation forms a latent radiation image on the screen by stimulating the storage layer. This latent radiation image can then be read by scanning the screen using a suitable electromagnetic wave radiation, such as visible light or infrared rays which releases the radiation energy stored in the storage layer as a light emission. The light emitted from the storage layer is then detected and converted into data corresponding to the image. Elimination of the image stored in the storage layer may be accomplished by exposing the storage layer for a period of time to a suitable electromagnetic wave radiation.
One type of storage layer radiation screen stores the radiation image in the form of an electrical charge distribution at a photo semiconductor layer. An example of this type of storage layer is described in Journal of Applied Photographic Engineering 4 178-182 (1978) which is incorporated herein by reference. Another type of storage layer radiation screen employs a luminophore, such as a phosphorescent material, which becomes excited when exposed to radiation. When the luminophore is exposed to stimulating rays, such as visible light, the luminophore releases energy in the form of light. Examples of this type of storage layer are described in U.S. Pat. Nos. 3,859,527 and 4,346,295 which are incorporated herein by reference.
As described in U.S. Pat. Nos. 4,258,264, 4,276,473, 4,315,318 and 4,387,428, stimulable phosphors have been proposed for use as luminophores in radiation image recording and reproducing systems. According to these systems, a screen containing a layer of a stimulable phosphor is exposed to radiation which has passed through an object being imaged, such as a part of the human body. The screen is then scanned with stimulating rays, such as a laser beam, which causes the phosphors in the screen to emit light in proportion to the amount of radiation absorbed by the portion of the screen being scanned. The light emitted by the screen is then detected and converted into an electrical signal. The electrical signal is then used to reproduce the radiation image as a visible image.
One particular application for radiation screens employing a storage layer, such as a stimulable phosphor, is in the area of dental radiography. Storage layer radiation screens have the significant advantage of requiring lower x-ray radiation levels to produce the radiation image. As a result, the amount of x-ray radiation that a patient is exposed to when a storage layer radiation screen is used is significantly reduced, thereby reducing the health risks associated with x-ray radiography. In addition, storage layer radiation screens can provide images with higher resolution than are provided by conventional dental x-ray films. U.S. Pat. No. 5,635,728 describes a scanner for reading storage layer screens used in dental radiography and is incorporated herein by reference.
In order for storage layer radiation screens to replace traditional dental radiation screens, it is important that the screens be easy to use. In particular, it is important that the screens be easily transferable from a patient's mouth to a scanner without significant image degradation. Furthermore, it is important that technicians be able to transfer the screens from the patient's mouth to a scanner without contaminating the scanner with infectious agents from the patient's mouth.
Storage layer radiation screens are generally enclosed within a barrier envelope when placed within a patient's mouth for dental imaging. This results in the contamination of the barrier envelope. The barrier envelope may be clear or opaque. Some dental technicians keep the storage layer radiation screen within the envelope during transport to a scanner. This creates the potential for contamination of items and areas away from the operatory. For example, the Soredex Digora scanner requires the technician to insert the storage layer radiation screen, still within the protective envelope, into a slot in the scanner. The technician moves a lever that causes a knife to cut off the end of the envelope. The technician then holds the open envelope up to another slot in the scanner whereby a magnet pulls the radiation screen out of the envelope through the slot into the interior of the scanner. The radiation screen is ejected back out of the same slot after reading. This procedure results in contamination of the knife, scanner, and the storage layer radiation screen. A need exists for a device that allows a technician to remove a screen from a contaminated envelop without contaminating the screen and then to transfer the screen to a scanner in an uncontaminated container.
Dental technicians and scanner operators generally wear gloves to protect themselves from infectious agents from the patients. The need to wear gloves increases the difficulty for the dental technician and scanner operator to handle the screens, remove the screens from the barrier envelopes, and load the screens onto the scanner. A need exists for a device and method which enables the screens to be separated from the barrier envelopes without contaminating the screens, thereby allowing the dental technicians and scanner operators to handle, transport and scan the screens without gloves in safety and without having to repeatedly put on new pairs of gloves.
Some dental technicians transport storage layer radiation screens from the patient to the scanner within a container exposed to ambient room light. This exposure to room light degrades the latent radiation images contained on the screens. Furthermore, transport in such an open manner commonly results in shadowing due to different sections of a screen being exposed to different amounts of light, and thus different degrees of latent image degradation, on the different sections of the radiation screens.
A need exists for a device that allows a technician to transport the light-sensitive storage layer radiation screens from the patient to a scanner within a dark environment protected from ambient light.